Traditional roofing materials are made up of two main components: a roofing membrane and an adhesive. Conventional adhesives are compounds derived from petroleum and are typically asphalt or bitumen compounds. The traditional application method for these materials was to first apply the adhesive to the surface of a roof and then to roll or stick the roofing membrane over the top of the adhesive. Asphalt or bitumen adhesives needed to be fluidized before application which required the use of processes such as hot mopping, open-flame torching, or the use of solvent-based cold process adhesives. These methods proved undesirable because they led to the release of fumes, odors, volatile organic compounds and created fire hazards. Such methods also require a higher level of skill and supervision for roofing workers in order to minimize safety risks and improper installation.
Self-adhering roofing systems provide an improvement on traditional roofing materials. As opposed to traditional roofing systems, self-adhering roofing systems contain three main components: a roofing material made up of a roofing membrane and a roofing adhesive, a silicone release coating, and a release liner. Roofing adhesives are typically petroleum products made up of asphalt or bitumen compounds. These adhesives are applied to a roofing membrane and then covered with a release liner coated with a silicone release coating on the surface of the release liner which contacts the roofing material. In this way, the release liner protects the roofing adhesive before use and prevents sticking. The three-layer roofing system is typically formed into rectangular strips and sold rolled into cylinders. For application, the roofing material is unrolled onto the roof, adhesive side down, and the release liner is removed, exposing the adhesive. These systems are preferred by builders in the industry and are fast becoming the industry standard because they reduce safety risks, are environmentally safe, and take less skill to apply.
Due to the widespread use of self-adhering roofing systems, there is a need in the industry for high functioning release liners. Specifically, effective release liners must remain adhered to the adhesive of the roofing material for long periods of time during storage, transport, and sale. It is important that the release liner maintains its adhesive ability throughout the interim between manufacture and use of the roofing system. Furthermore, release liners must not interact with or absorb portions of the roofing adhesive, or materials from other layers of the self-adhering roofing systems which can cause staining of the release liner and/or lower the effectiveness of the adhesive.
Petroleum based roofing adhesives contain oil components which are prone to migration into conventional release liners. Such oil migration can cause staining of the release liner, which is unsightly and may deter buyers as it signifies an inferior product to consumers. Furthermore, oil migration into the release liner may cause the adhesive to lose its stickiness and adhesive ability. These problems are exacerbated in warm or hot temperatures, which decrease the viscosity of the asphalt or bitumen adhesives and increase oil diffusion rates. As self-adhering roofing systems may be installed in warm, sunny, or even hot weather conditions, release liners that minimize oil migration are particularly advantageous.